The present invention relates in general to plastic plugs that are constructed and arranged to assemble into a container opening, typically by threading. The opening may be formed directly into the container or may be defined by a threaded flange. More specifically, the present invention relates to the described style of plastic plug that receives an overcap. Preferably the overcap is constructed and arranged to assemble to the plastic plug and/or container with a tamper-evident configuration and function. In the preferred embodiment the plastic plug is a unitary, molded component and the overcap is a unitary, molded plastic component. These two components are pre-assembled prior to plug insertion into the container opening without any overcap connection to the container.
When designing a closure or closure assembly that preferably includes a tamper-evident configuration or construction, it is important to consider the overall design efficiency, the reliability of the component parts as assembled and as installed, the overall cost, the physical size and the overall aesthetics, to mention some of the relevant considerations. Reliability includes not only how the tamper-evident construction functions in terms of properly revealing when a tampering attempt has been made, but also in not prematurely failing or showing a tampering attempt when none was made.
In one prior art construction, the tamper-evident component is a plastic cover that includes a skirt that cooperates with ratchet projections on an outer surface of the container opening. The size and shape complexity of this tamper-evident component adds to the component cost. The plastic plug threads into the neck opening of the container and then the tamper-evident component is engaged on the container.
In another prior art construction the tamper-evident component is of a part-metal construction in combination with a plastic overcap. A metal ring overlays the plastic skirt of the overcap such that crimping of the metal ring causes the plastic skirt to be crimped around a cooperating form on the outer surface of the container neck opening, after the plastic plug is threaded into the neck opening of the container. This tamper-evident component, similar to the first-described prior art component, is a more costly component that requires a specific style of container due to the structural cooperation between the tamper-evident overcap and the container.
In contrast to these prior art examples, the tamper-evident overcap described herein as one embodiment of the present invention provides a simpler design that engages only the plug, providing greater versatility since the container style does not have to be selected to cooperate with a particular style of tamper-evident overcap. While the plastic plug construction that is part of the prior art and depicted in part as one portion of the present disclosure includes interior structural features or forms for facilitating the threading of the plug into and out of the container neck opening, the present invention does not use those features for the initial assembly of the plug and overcap combination into the container neck opening. Instead, according to one embodiment of the present invention the tamper-evident overcap is preassembled to the plastic plug and those plug features (interior) that might otherwise be used for tightening the plastic plug into the neck opening are covered by the tamper-evident overcap. The plug and overcap constructions disclosed herein require a different method of installation and different tooling, both of which are described herein and both of which constitute an aspect of this overall invention.
The present disclosure provides a simple and reliable and aesthetically-pleasing, low cost tamper-evident overcap that assembles to the plastic plug. The overcap does not interface with the container neck opening, thereby allowing a wider range of container neck styles that remain compatible with the threaded plug. This wider range of container neck opening styles also remains compatible with the tamper-evident overcap as disclosed herein. Each outer peripheral portion of the plastic plugs disclosed herein includes unique structural forms that interfit with a unique installation tool for advancing the plug into the container opening. This unique installation tool can also be used for removing the plug from the container opening. The plug styles disclosed herein in combination with the unique installation tool comprises a container closure system.